1. Field of the Invention
The present invention relates to a magnetic tape cartridge used mainly for an 8 mm video tape recorder. More particularly, it relates to structure of a pivot pin as well as a supporting member thereof for a lid which is mounted on a pair of upper and lower casings and which is swingable between opening and closing positions.
2. Description of Prior Art
Magnetic tapes for video recorders have been widely used. The magnetic video tapes widespread at present are standardized as a half inch (12.65 mm) width type. However, it is estimated that demand for a small-sized video tape cartridge will increase in view of requirements in feasibility of handling and transporting. In response to such requirements, an 8 mm video tape has been developed. An 8 mm video tape cartridge should be, of course, reduced in size in comparison with a currently used video tape cartridge. However, only reduction in size of structural elements of an operating mechanism could not provide a satisfactory product and therefore, it is required to totally review the structural elements of the operating mechanism and their positional relationship. As the elements become smaller, it becomes difficult to assure reliability during operations of these elements and feasibility in assembling. When the construction having been conventionally used is utilized without change, trouble may be caused at the time of assembling and operations.
FIG. 1 shows the outer configuration of a typical 8 cm video tape cartridge, the dimension being 9.4 cm long, 6 cm wide and 1.5 cm thick. The cartridge comprises an upper half casing 1, a lower half casing 2 and a lid 3 mounted in the front of the casings so as to be opened and closed. The lid 3 is constructed in such a manner that when the video tape cartridge is placed on a video tape recorder, it is opened to expose a magnetic tape extending in the front portion inside the cartridge at the side of the rotating magnetic head and when the cartridge is removed from the video tape recorder, it automatically closed to protect the magnetic tape in the time of non-use. To allow the lid to be opened and closed, a pivot pin 5 is formed in the inner wall of each ear 4 formed at both sides of the lid 3 and each of the pivot pins 5 is supported by each of supporting openings provided by the upper and lower casings. Thus, the lid can be swung between an opened position and a closed position around the pivot pin 5. Specifically, as shown in FIG. 2, the pivot pin 5 is supported by fitting it in an opening 6 formed between the upper half casing 1 and the lower half casing 2. When the lid is to be assembled, the lid 3 is first mounted on the upper half casing 1 so that the pivot pin 5 comes to the shoulder portion of the upper half casing and then, the lower half casing 2 is coupled to the upper half casing so as to determine their positional relationship. In the assembling operations, therefore, the pivot pin 5 is apt to come out, on account of which an auxiliary supporting member is needed during the assembling operations. Accordingly, it is difficult to employ automatic operations for assemblage and the pivot pin may come out after completing of assemblage.